The possibilities of human hearing are much inferior to those of animals. And in order to hear something better, we put a palm folded in a boat to our ear and this helps. It was on such attempts to expand and lengthen the auricle that the principle of operation of hearing horns for the deaf, which began to be produced in the middle of the 19th century, was based.
At about the same time, aviation began to develop, including the military. But how to hear the approach of an airplane in time to protect yourself from flying death? Scientists happily seized on the idea of auditory horns and began to work hard in this direction, having produced the progenitor of radar systems - a giant bell and an ear for it.
Hearing aids in the army
Japanese Emperor Hirohito inspects a combat auditory tube unit, 1930s:
Early warning system of ships
The British even built sound mirrors. Huge concrete towers in the form of parabolic plates and a curved wall served for early detection of enemy ships.
Acoustic locators of besieged Leningrad
The auditory means of detecting aircraft were used even during the Great Patriotic War. During the blockade of Leningrad, the blind worked alongside the sighted fighters in the air defense systems. The idea to recruit the blind to work on acoustic devices appeared at the headquarters of the city air defense and brought unexpected results. For several tens of kilometers, a blind listener could not only find out about the approach of an aircraft, but also determine its make. Rumors easily distinguished Soviet planes from fascist ones and, moreover, by the noise of the engine, they informed the anti-aircraft gunners that the Heinkel or Junkers was approaching.
With the development of electronics, the acoustic branch of the location died, and the fighting Cheburashkas now use highly sensitive electronic devices and no longer wear big ears. However, such monsters can still be found in various museums.